Twin Merc 275s RPM's drop to 1000rpm with each wave
I have a 30' center console with two Merc 275's. They'll be running strong at 4000RPM but when it's a bit choppy they will act up. As each wave is hit the engines will go from 4000RPM to 1000RPM and then back to 4000RPM. It happens on every wave. Sometimes they drop so much that they stall out, sometimes the port engine is worse. The fuel tank is full and they otherwise run ok. Any ideas?